Mechanical Engineering Commons^™

High Injection Pressure Dme Ignition And Combustion Processes: Experiment And Simulation, Xiucheng Zhu

Dissertations, Master's Theses and Master's Reports

With nearly smokeless combustion, Dimethyl Ether (DME) can be pressurized and used as a liquid fuel for compression-ignition (CI) combustion. However, due to its lower heating value and liquid density compared with diesel fuel, DME has a smaller energy content per unit volume. To obtain an equivalent energy content of diesel, approximately 1.86 times more quantity of DME is required. This can be addressed by a larger nozzle size or higher injection pressure. However, the effect of high injection pressure on DME spray combustion characteristics have not yet been well understood. In order to fill this gap, spray and combustion …

Optimization And Comparison Of Over-Expanded And Other High Efficiency Four-Stroke Spark-Ignited Boosted Engines, Zhuyong Yang

Dissertations, Master's Theses and Master's Reports

Recent fuel economy and emission regulations are the major concern of the research and development of modern internal combustion engine. Such technologies include variable valve timing (VVT), direct injection (DI), turbocharging, downsizing, and over-expanded cycle are used by many manufacturers to improve engine fuel economy or increase power density.

Current Atkinson cycle technology in the production engine is mainly realized by an advanced valvetrain system to reduce the effective compression ratio while maintaining the same expansion ratio. Another approach to realize over-expanded cycle engine is to utilize a multi-link cranktrain mechanism. Although the Atkinson cycle was originally patented in the …

Multi-Scale, Capillary Assisted Copper Surfaces For Enhanced Pool Boiling Heat Transfer Processes, Chetan Agarwal

Dissertations, Master's Theses and Master's Reports

Phase-change heat transfer through pool boiling process offers a promising thermal management solution in applications wherein conventional air or single-phase liquid-based cooling methods prove inefficient such as for high-power electronics. Pool boiling process, which utilizes the latent heat of evaporation, provides a robust and efficient way to efficiently dissipate the excessive heat generated in a small footprint area in particular as seen in CPUs (Central Processing Units), GPUs (Graphics Processing Units), LEDs (Light Emitting Diodes), radars, and other demanding computing, sensing and surveillance electronics. Although boiling process has been studied for over five decades, it has not been yet adapted …

Influence Of Micro-Nucleate Boiling On Annular Flow Regime Heat Transfer Coefficient Values And Flow Parameters – For High Heat-Flux Flow Boiling Of Water, Soroush Sepahyar

Dissertations, Master's Theses and Master's Reports

Analysis of results from steady and steady-in-the-mean high heat-flux (15 - 70 W/cm², with water as working fluid) shear driven annular flow-boiling experiments presented here - and low heat-flux (0.1- 1 W/cm², with FC-72 as working fluid) experiments presented elsewhere – together lead to a key conclusion. The conclusion is that heat carrying nucleation rates go often undetected by the typically used visualization approaches for flow boiling – as such flows often involve µm- to sub- µm scale bubble diameters in millimeter-scale ducts. These nucleation rates play a significant role in most of the so-called convective …

Modeling And Control Of Maximum Pressure Rise Rate In Rcci Engines, Aditya Basina

Dissertations, Master's Theses and Master's Reports

Low Temperature Combustion (LTC) is a combustion strategy that burns fuel at lower temperatures and leaner mixtures in order to achieve high efficiency and near zero NOx emissions. Since the combustion happens at lower temperatures it inhibits the formation of NOx and soot emissions. One such strategy is Reactivity Controlled Compression Ignition (RCCI). One characteristic of RCCI combustion and LTC com- bustion in general is short burn durations which leads to high Pressure Rise Rates (PRR). This limits the operation of these engines to lower loads as at high loads, the Maximum Pressure Rise Rate (MPRR) hinders the use of …

Development Of A 2d Scr Catalyst On A Diesel Particulate Filter Model For Design And Control Applications To A Ultra Low Nox Aftertreatment System, Venkata Chundru

Dissertations, Master's Theses and Master's Reports

This research focuses on modeling and control of PM and NO_x in diesel engine exhaust using an SCR catalyst on a Diesel Particulate Filter (SCR-F). A 2D SCR-F model was developed that is capable of predicting internal states: 2D temperature, PM and NH₃storage distributions and filtration efficiency, pressure drop, PM mass retained in the PM cake and substrate wall and outlet NO, NO₂and NH₃concentrations. The SCR-F model was used to simulate a DOC + SCR-F + DOC + SCR ultra-low NOx system that can achieve > 99.5% NOx conversion efficiency.

The model was calibrated …

Networked Microgrid Optimization And Energy Management, Robert S. Jane

Dissertations, Master's Theses and Master's Reports

Military vehicles possess attributes consistent with a microgrid, containing electrical energy generation, storage, government furnished equipment (GFE), and the ability to share these capabilities via interconnection. Many military vehicles have significant energy storage capacity to satisfy silent watch requirements, making them particularly well-suited to share their energy storage capabilities with stationary microgrids for more efficient energy management. Further, the energy generation capacity and the fuel consumption rate of the vehicles are comparable to standard diesel generators, for certain scenarios, the use of the vehicles could result in more efficient operation. Energy management of a microgrid is an open area of …

Paddle Mixer-Extrusion Reactor For Torrefaction And Pyrolysis, Stas Zinchik

Dissertations, Master's Theses and Master's Reports

This work is focused on the fundamental understanding and the development of paddle mixer reactors (or modified screw augers). This work will contribute to the effort of the thermal conversion of biomass and wastes. We developed and studied two paddle systems (i) 25-mm lab-scale (up to 1 kg/hr) and (ii) 101-mm pilot-scale (up to 100 kg/hr). Thermal behavior of the two systems was studied and it was estimated that the lab-scale system has a high heating rate of up to 530 °C/s. Residence times were thoroughly measured and were determined as a function of rotation frequency and volume fraction. We …